Shares in SoftBank retreated again on Tuesday, bringing losses in Japan to 7.7 per cent over two days following reports that the conglomerate had been making huge and risky bets on tech stocks, CNN reported.

The losses have wiped roughly $10 billion off the market value of SoftBank. How big are the bets? SoftBank bought $4 billion worth of options tied to underlying shares it had earlier purchased in tech firms like Amazon, Microsoft and Netflix, according to the Wall Street Journal. The newspaper said that the options generated an exposure of about $50 billion.

The size of the bets means that SoftBank CEO Masayoshi Son is now being called a "whale" — a heavy hitter with the power to move markets on his own. But investors in his company are nervous.